Oblique expanding fusion cage device and method

ABSTRACT

An oblique expanding fusion cage device including a body with a superior portion and an inferior portion. The superior portion and the inferior portion have a proximal end and a distal end. The fusion cage device also includes a pathway, an opening, and an expanding member. The pathway travels from the proximal end to the distal end of the device between the superior and inferior portions. The opening in the proximal end of the body enables access to the pathway. The expanding member may be removably inserted into the opening and is moveable toward the distal end of the body, wherein the expanding member engages the superior portion and the inferior portion as the expanding member moves distally within the pathway.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. application Ser. No. 14/442,974 filed May 14, 2015, which issues as U.S. Pat. No. 9,907,671 on Mar. 6, 2018, which is a 371 U.S. National Stage of International Application No. PCT/US2013/070427, filed Nov. 15, 2013, which claims the benefit of and priority to U.S. Provisional Application No. 61/727,504, filed Nov. 16, 2012. The entire disclosures of each of the above applications are incorporated herein by reference.

TECHNICAL FIELD

The present application relates generally to general surgery and orthopedic and neurosurgical implants used for insertion within a space between a patient's vertebrae. More specifically, but not exclusively, the present invention concerns oblique expanding fusion cage devices implanted in the spine to maintain or re-establish proper spacing between a patient's vertebrae.

BACKGROUND

Fusion of the lumbar and thoracic spine currently involves implants and methods of maintaining or re-establishing the spacing within the spine. Many of the known implants do not accurately fit the interbody space and may result in decreased probability of fusion and cage migration.

SUMMARY

Various embodiments described herein relate to adjustable, oblique expanding fusion cage devices and methods that can maintain or re-establish anatomic spacing within a patient's spine.

In some embodiments, an oblique expanding fusion cage device including a body with a superior portion and an inferior portion is disclosed. The superior portion and the inferior portion have a proximal end and a distal end. The fusion cage device also includes a pathway, an opening, and an expanding member. The pathway travels from the proximal end to the distal end of the device between the superior and inferior portions. The opening in the proximal end of the body enables access to the pathway. The expanding member may be removably inserted into the opening and is moveable toward the distal end of the body, wherein the expanding member engages the superior portion and the inferior portion as the expanding member moves distally within the pathway.

In some embodiments, a surgical method for maintaining a vertebral interbody space in a spine of a patient is disclosed. The method includes the steps of obtaining a medical device and inserting the medical device into a patient through an opening in the skin. The medical device includes a body with a superior portion and an inferior portion. The superior portion and the inferior portion include a proximal end and a distal end. The fusion cage device also includes a pathway, an opening, and an expanding member. The pathway travels from the proximal end to the distal end of the device between the superior and inferior portions. The opening in the proximal end of the body enables access to the pathway. The expanding member may be removably inserted into the opening and is moveable toward the distal end of the body, wherein the expanding member engages the superior portion and the inferior portion as the expanding member moves distally within the pathway. The method also includes the steps of positioning the medical device in the vertebral interbody space and inserting the expanding member into the body of the medical device. Finally, the method includes the step of deploying the distal end of the medical device to engage two vertebrae adjacent to the vertebral interbody space.

These, and other objects, features and advantages of the embodiments described herein will become apparent from the following detailed description of the various aspects of the invention taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the device and methods described herein and together with the detailed description herein, serve to explain the principles devices and methods described herein. The drawings are only for purposes of illustrating preferred embodiments and are not to be construed as limiting.

FIG. 1 is an end view of an obliquely expanding fusion cage device in an undeployed position, in accordance with various embodiments disclosed herein;

FIG. 2 is an end view of the fusion cage device of FIG. 1 in a deployed position, in accordance with various embodiments described herein;

FIG. 3 is a side view of the fusion cage device of FIG. 1, in accordance with various embodiments described herein;

FIG. 3A is a side view of the fusion cage device of FIG. 1, in accordance with various embodiments described herein;

FIG. 4 is a side view of two expanding members for the fusion cage device of FIG. 1, in accordance with various embodiments described herein;

FIG. 5 is an exploded side view of the fusion cage device of FIG. 1, in accordance with various embodiments described herein;

FIG. 6 is a lateral view of a fusion cage device and an expanding member, in accordance with various embodiments described herein;

FIG. 7 is a lateral view of the fusion cage device of FIG. 6 with the expanding member partially inserted into an inferior portion of the fusion cage device, in accordance with various embodiments described herein;

FIG. 8 is a lateral view of the fusion cage device of FIG. 6 with the expanding member fully inserted into the inferior portion of the fusion cage device, in accordance with various embodiments described herein;

FIG. 9 is a lateral view of a fusion cage device with an expanding member, in accordance with various embodiments described herein;

FIG. 10 is a lateral view of a fusion cage device, in accordance with various embodiments described herein;

FIG. 11 is a proximal view of a fusion cage device, in accordance with various embodiments described herein;

FIG. 12 is a distal view of the fusion cage device of FIG. 11, in accordance with various embodiments described herein;

FIG. 13 is a lateral cross-sectional view of the fusion cage device of FIGS. 11 and 12 in an undeployed position, in accordance with various embodiments described herein;

FIG. 14 is a lateral cross-sectional view of the fusion cage device of FIGS. 11-13 in a deployed position, in accordance with various embodiments described herein;

FIG. 15 is a proximal view of a fusion cage device, in accordance with various embodiments described herein;

FIG. 16 is a lateral cross-sectional view of the fusion cage device of FIG. 15, in accordance with various embodiments described herein;

FIG. 17 is a lateral cross-section view of the fusion cage device of FIGS. 15 and 16 in an undeployed position with the expanding member partially inserted, in accordance with various embodiments described herein;

FIG. 18 is a lateral cross-section view of the fusion cage device of FIGS. 15-17 in a deployed position with the expanding member fully inserted, in accordance with various embodiments described herein;

FIG. 19 is a lateral cross-sectional view of a fusion cage device in an undeployed position, in accordance with various embodiments described herein;

FIG. 20 is a lateral cross-section view of the fusion cage device of FIG. 19 in a partially deployed position, in accordance with various embodiments described herein;

FIG. 21 is a proximal view of a fusion cage device, in accordance with various embodiments described herein;

FIG. 22 is a distal view of the fusion cage device of FIG. 21, in accordance with various embodiments described herein;

FIG. 23 is a partially exploded lateral cross-sectional view of the fusion cage device of FIGS. 14 and 15 with an expanding member being inserted into the fusion cage device, in accordance with various embodiments described herein;

FIG. 24 is a lateral view of an expanding member, in accordance with an various embodiments described herein;

FIG. 25 is a lateral view of an expanding member, in accordance with various embodiments described herein;

FIG. 26 is a lateral view of an expanding member, in accordance with various embodiments described herein;

FIG. 27 is a lateral view of an expanding member, in accordance with various embodiments described herein; and

FIG. 28 is a proximal view of the fusion cage device of FIG. 21 with an alternative locking mechanism, in accordance with various embodiments described herein.

DETAILED DESCRIPTION

Generally stated, disclosed herein are a number of embodiments of oblique expanding fusion cage devices. As used herein, the terms “obliquely expanding fusion cage device,” “fusion cage device,” “interbody fusion cage,” “fusion cage,” “device,” and “cage implant” may be used interchangeably as they essentially describe the same type of device. Further, a surgical method for using the fusion cage devices to maintain a space between two vertebral bodies within a patient suffering from a diseased or damaged spinal column is discussed.

In this detailed description and the following claims, the words proximal, distal, anterior, posterior, medial, lateral, superior and inferior are defined by their standard usage for indicating a particular part of a bone or implant according to the relative disposition of the natural bone or directional terms of reference. For example, “proximal” means the portion of an implant nearest the torso, while “distal” indicates the portion of the implant farthest from the torso. As for directional terms, “anterior” is a direction towards the front side of the body, “posterior” means a direction towards the back side of the body, “medial” means towards the midline of the body, “lateral” is a direction towards the sides or away from the midline of the body, “superior” means a direction above and “inferior” means a direction below another object or structure. In addition, for the purposes of this disclosure when referencing the device, the term “proximal” will mean the portion of the device closest or nearest the insertion instrument. The term “distal” shall mean the portion of the device farthest away from the insertion instrument.

Referring to the drawings, wherein like reference numerals are used to indicate like or analogous components throughout the several views, and with particular reference to FIGS. 1-5, there is illustrated an exemplary embodiment obliquely expanding fusion cage device 10. The fusion cage device 10 may have a generally rectangular or trapezoidal shape in the undeployed position to facilitate insertion into a patient's spine, although other shapes are possible. The fusion cage device 10 may also be narrower at a distal end 12 than at a proximal end 14 in the undeployed position for ease of insertion into the patient's spine. In the deployed position the fusion cage device 10 may have a generally trapezoidal shape to fill the interbody space. The fusion cage device 10 may include a superior portion 16 overlapping an inferior portion 18. The profile of the proximal and distal ends 14, 12, respectively, of the superior portion 16 and inferior portion 18 may be semi-circular halves fitted together and overlapping interiorly. The superior portion 16 may have a generally rectangular shaped lateral side with a plurality of openings 30 which include engagement teeth 32. The inferior portion 18 may have a generally rectangular shaped lateral side with a plurality of protrusions 34 which include engagement tabs 36 for engaging the engagement teeth 32 of the openings 30 in the superior portion 16.

The proximal end 14 may also include an opening 20 mating with a channel 22. As best shown in FIGS. 3, 3A and 5, the opening 20 may be comprised of slanted portions in both the superior portion 16 and the inferior portion 18. The slanted portions are slant inwardly and medially (i.e., towards the center of the device 10). The inwardly slanted portions in the superior and inferior portions 16, 18 may each have a semi-circular shape when viewed from the proximal end 14 (see, e.g., FIGS. 1 and 2) such that when the device 10 is in the undeployed position, the two slanted portions come together to form an opening 20 having a cone-shaped depression that can funnel an expanding member towards the channel 22.

The channel 22 is generally formed in the inferior portion 18. As shown in, for example, FIG. 3A, the channel 22 is generally made up of a series of aligned passages that extend through each of the protrusions 34 in the inferior portion 18. The shape of the channel 22 is generally not limited. As shown in, for example, FIGS. 1 and 2, the channel 22 has a square cross-sectional shape. Other shapes, such as a circular shape, can be used. The cross-sectional dimensions of the channel 22 are not limited, but are generally selected to accommodate expanding members with a variety of diameters. Generally speaking, the diameter of the expanding member will dictate how far the superior portion 16 can be moved away from the inferior portion 18 in a deployed position. As a result, the cross sectional dimensions of the channel 22 should be at least equal to the desired maximum distance of separation between the superior portion 16 and the inferior portion 18. The channel 22 may be uniform or narrow as it travels from the opening 20 at the proximal end 14 of the device 10 to the distal end 12. The opening 20 and channel 22 may be generally centered in a medial-lateral direction on the device 10.

An expanding member 24 may be inserted into the opening 20 and moved distally along the channel 22. As the expanding member 24 moves into the device 10, the expanding member 24 engages the superior portion 16 and the inferior portion 18 and moves the superior portion 16 away from the inferior portion 18 such that the device 10 fills the patient's intervertebral body space. As the expanding member 24 expands the cage device 10 the engagement tabs 36 move distally in the openings 30 and the tabs 36 are forced past the teeth 32 as the cage device 10 expands. The device 10 with an expanding member 24 inserted into the channel 22 is shown in FIG. 3A.

The expanding member 24 may be a screw or the like. The expanding member 24 may come in multiple sizes to provide varying amounts of expansion of the cage device 10. The expanding member 24 with a smaller diameter threaded shaft 26 will expand the cage device 10 less than an expanding member 24 with a larger diameter threaded shaft 28.

FIGS. 6-8 show various embodiments of a fusion cage device 50. In an undeployed position the fusion cage device 50 may have a rectangular or trapezoidal shape to facilitate insertion between two vertebrae of a patient. In addition, for ease of insertion, the distal end 52 of the device 50 may be narrower than the proximal end 54 of the device 50 in an undeployed position. In a deployed position the fusion cage device 50 may have a generally trapezoidal shape as the device 50 deploys to fill the space between two vertebrae. The fusion cage device 50 may include a superior portion 56 adjacent an inferior portion 58 and a deployment portion 60. The deployment portion 60 can be generally parallel to the superior portion 56 in an undeployed position and generally perpendicular to the superior portion 56 when deployed. The deployment portion 60 may be hinged to the superior portion 56, enabling the deployment portion 60 to swing open as it is engaged by an expanding member 62. Alternatively, the deployment portion 60 may be hinged to the inferior portion 58 enabling the deployment portion 60 to swing open as it is engaged by the expanding member 62.

An expanding member 62 may be inserted into an opening 64 in the proximal end 54 of the device 50 to engage the inferior portion 58 and the deployment portion 60. The expanding member 62 may be a screw which includes a drive head 66 and a threaded shaft 68. As the expanding member 62 is moved from the proximal end 54 to the distal end 52 of the device 50 the deployment portion 60 is pushed from a generally parallel position, as seen in FIG. 6, to a partially deployed position, as seen in FIG. 7, and finally reaches a fully deployed position, as shown in FIG. 8, wherein the deployment portion 60 is generally perpendicular to the superior portion 56. The inferior portion 58 may include a threaded channel 70 wherein the threads of the threaded channel 70 correspond with the threads on the expanding member 62. When the expanding member 62 is fully inserted into the device 50, the deployment portion 60 will be in a fully deployed position generally perpendicular to the superior portion 56. As the deployment portion 60 is deployed, it extends the distal end 52 of the device 50 and in turn distracts the distal portion of the intervertebral space.

FIG. 9 shows various embodiments of a fusion cage device 80. In an undeployed position the fusion cage device 80 may have a rectangular or trapezoidal shape to facilitate insertion between two vertebrae of a patient. In addition, a distal end 82 of the device 80 may be narrower than a proximal end 84 of the device 80 in an undeployed position. In a deployed position the fusion cage device 80 may have a generally trapezoidal shape as the device 80 deploys to fill the space between two vertebrae. The fusion cage device 80 may include a superior portion 86 adjacent an inferior portion 88 and a deployment portion 90. The deployment portion 90 is generally parallel to the superior portion 86 in an undeployed position and generally perpendicular to the superior portion 86 when deployed. A deployment mechanism (not shown) may be inserted into an opening in the proximal end 84 of the device 80 to engage the superior portion 86, inferior portion 88, and deployment portion 90. The deployment mechanism may be a screw or the like, such as described above with reference to FIGS. 6-8. As the deployment mechanism is moved from the proximal end 84 to the distal end 82 of the device 80 the deployment portion 90 is pushed from a parallel position to a perpendicular deployed position as shown in FIG. 9. In some embodiments, the deployment portion 90 can be hingedly coupled at one end with distal end 82 of the superior portion 86 so that the deployment portion 90 can hinge between a undeployed configuration and a deployed configuration. When the deployment mechanism has been fully inserted into the device 80, the deployment portion 90 will be in a fully deployed position generally perpendicular to the superior portion 86. In addition, as the deployment mechanism is advanced toward the distal end 82 of the device 80, the inferior portion 88 may deploy distally. As the inferior portion 88 and the deployment portion 90 are deployed they distract the distal end 82 of the device 80 and in turn distract the distal portion of the intervertebral space.

FIG. 10 illustrates various embodiments of an obliquely expanding fusion cage device 100 including a proximal end 102 and a distal end 104. The undeployed fusion cage device 100 may have a rectangular or trapezoidal shape to facilitate insertion into the patient's spine. To help facilitate the insertion of the device 100 into a patient's spine the distal end 104 may also be narrower than the proximal end 102 of the device 100 in the undeployed position. The fusion cage device 100 may have a trapezoidal shape in the deployed position to fill or expand the intervertebral disc space. The fusion cage device 100 may include a superior portion 106 hingedly connected to an inferior portion 108 and an expanding member 110 for engaging the superior and inferior portions 106, 108, respectively. The superior portion 106 and inferior portion 108 may be hingedly connected at the proximal end 102. The superior portion 106 and the inferior portion 108 may also each have a relatively trapezoidal shape. The superior portion 106 and inferior portion 108 may each be larger at the distal end 104 than the proximal end 102. As the expanding member 110 is inserted into an opening in the proximal end 102 of the device 100 the expanding member 110 engages the interior surface of each of the superior portion 106 and the inferior portion 108. As the expanding member 110 is advanced toward the distal end 104 of the device 100 the superior portion 106 and inferior portion 108 are expanded away from each other to fill or expand the intervertebral disc space. The expanding member 110 may be a screw or similar expansion mechanism.

Referring now to FIGS. 11-14, various embodiments of an expanding fusion cage device 150 are illustrated. The fusion cage device 150 may be generally rectangular or trapezoidal in shape when undeployed. In addition, the distal end 156 may be narrower than the proximal end 154 to assist in insertion of the device 150 between two adjacent vertebrae. Once deployed the cage device 150 will likely have a distal end 156 that is wider than the proximal end 154. Fusion cage device 150 includes a body 152 with a proximal end 154 and a distal end 156. The body 152 may include a center opening 158 for receiving a curved shim 160 which may be attached to an expanding member 162. The curved shim 160 may be made of a variety of biocompatible materials, including, but not limited to, titanium, stainless steel, PEEK, or a memory metal, such as Nitinol. The expanding member 162 may be inserted into the opening 158 at the proximal end 154 of the body 152 to move the curved shim 160 toward the distal end 156. The expanding member 162 may be a screw which may be turned to advance the shim 160 along the opening 158 to the distal end 156. The expanding member 162 may include a threaded shaft which engages a threaded surface on the interior of the body 152 when inserted into the center opening 158. When the shim 160 reaches the distal end 156 of the body 152 it may exit the opening 158 at the distal end 156 and curve to contact a cephalad or caudal endplate when completely deployed. The cephalad or caudal endplate is displaced distally as the shim 160 pushes against the endplate.

Various embodiments of an expanding fusion cage device 200 are illustrated in FIGS. 15-18. The fusion cage device 200 may have a generally rectangular or trapezoidal shape in the undeployed position, as illustrated in FIG. 17, to facilitate insertion between two vertebrae. In addition, in the undeployed position the fusion cage device 200 may be narrower at a distal end 202 than a proximal end 204. In the deployed position, shown in FIG. 18, the fusion cage device 200 will have a generally trapezoidal shape to fill the interbody space and enable fusion between the two vertebrae. The fusion cage device 200 may include a superior portion 206 adjacent an inferior portion 208 which in an undeployed position creates an opening 210. The opening 210 may be tapered from the proximal end 204 to the distal end 202 for mating with an expanding member 212. As the opening 210 tapers toward the distal end 202 it may narrow to be much smaller than the width of the expanding member 212. The opening 210 may be accessed at the proximal end 204 through a hole 214. The hole 214 may be nearly identical to the size of the expanding member 212. The expanding member 212 may be a screw, sliding member, or like expansion mechanism. A screw-like expanding member 212 may include a threaded end. As the expanding member 212 is inserted into the opening 210 it interacts with the interior surfaces 207, 209 of the superior portion 206 and the inferior portion 208 forcing the superior portion 206 and the inferior portion 208 to separate. In some embodiments, the superior portion 206 and the inferior portion 208 each about their proximal end 204 when being separated such that the interior surfaces 207, 209 go from an angled orientation in the undeployed state to a generally parallel orientation in the deployed state.

If a screw-like expanding member 212 is used the interior surfaces 207, 209 of the distal end 202 of the superior and inferior portions 206, 208 may be threaded to mate with a corresponding threaded portion of the expanding member 212. Alternatively, if a sliding type expanding member 212 is used the sliding type member 212 may be pushed into the interior surfaces 207, 209 of the superior and inferior portions 206, 208 at the distal end 202 of the cage device 200 forcing the superior and inferior portions 206, 208 apart. In a fully deployed position the sliding type member 212 is fit into a locking mechanism (not shown) which secures the sliding type member 212 to the device 200. As the superior portion 206 and inferior portion 208 separate, the distal end 202 of the device 200 displaces both cephalad and caudally relative to the proximal end 204.

Referring now to FIGS. 19 and 20, various embodiments of an expanding fusion cage device 250 are shown. The fusion cage device 250 includes a first arm 252 parallel to a second arm 254 and an expanding member 256. The expanding member 256 may include a body 258 at the proximal end 253 and a wedge 264 at the distal end 251. A winding mechanism 266 may be coupled to the body 258. The winding mechanism 266 and the wedge 264 may be connected by a cable 268. The cable 268 may run between and parallel to the first arm 252 and the second arm 254. The first arm 252 may be attached to the body 258 of the expanding member 256 with a pivot pin 260 and the second arm 254 may be attached to the body 258 of the expanding member 256 with a pivot pin 262, enabling the first arm 252 and second arm 254 to spread apart as the wedge 264 is pulled toward the proximal end 253 by the cable 268. The cable 268 may be pulled by turning the winding mechanism 266. As the first and second arms 252, 254 separate, they cause distraction of the cephalad and caudal vertebral elements distally while maintaining the proximal position.

Various embodiments of an expanding fusion cage device 300 are shown in FIGS. 21-23 and 28. The fusion cage device 300 may have a generally rectangular or trapezoidal shape in an undeployed position. The fusion cage device 300 may be narrower at a distal end 310 than at the proximal end 308 in the undeployed position. In the deployed position the fusion cage device 300 will have a generally trapezoidal shape. The fusion cage device 300 may include a superior portion 302 adjacent to an inferior portion 304 and separated by an opening 306. The opening 306 may extend from a proximal end 308 to a distal end 310. The proximal end 308 may also include a pathway 312 and a locking mechanism 314. The pathway 312 may extend from the proximal end 308 to the distal end 310. The pathway 312 may taper as it extends from the proximal end 308 to the distal end 310. The tapered pathway 312 may enable an expanding member 316, such as a screw, to expand the distal end 310 of the device 300 as the expanding member 316 is inserted farther into the pathway 312. The pathway 312 may also be threaded 318 to correspond to the threads 320 on the expanding member 316. The expanding member 316 may include a shaft 324 with a head 326 at a first end which may include a drive opening 322 for advancing the expanding member 316 down the pathway 312. Once the shaft 324 of the expanding member 316 is fully inserted into the pathway 312 the locking mechanism 314 may secure the head 326 of the expanding member 316 into the device 300. The locking mechanism 314 may be a locking collar, although other locking mechanisms are also contemplated, such as a cam lock 328, as illustrated in FIG. 28.

The expanding member 316 may be provided in a number of sizes, as illustrated in FIGS. 24-27, depending on the desired expansion of the distal end 310. The expanding member 316 shown in FIG. 24 will provide the largest expansion of the distal end 310 of device 300, while the expanding member 316 illustrated in FIG. 27 will provide the smallest expansion of the distal end 310 of device 300 and the expanding members 316 of FIGS. 25 and 26 will provide intermediate amounts of expansion of the distal end 310. As illustrated, the longer the length of the expanding member 316 the greater the height of expansion the device 300 experiences at its distal end 310.

The obliquely expanding fusion cage devices 10, 50, 80, 100, 150, 200, 250, and 300 may be made of a variety of biocompatible materials, such as, stainless steel, titanium, PEEK, and the like. The devices 10, 50, 80, 100, 150, 200, 250, and 300 may be coated with a substance or material, such as, plasma coating or surface etching, to assist with biocompatibility and help reduce wear. The devices 10, 50, 80, 100, 150, 200, 250, and 300 may also come in various sizes. For example, the devices 10, 50, 80, 100, 150, 200, 250, and 300 may have undeployed heights ranging from approximately six to eighteen millimeters, undeployed widths ranging from approximately eight to fifteen millimeters, and undeployed lengths ranging from approximately twenty to thirty-five millimeters.

The fusion cage devices 10, 50, 80, 100, 150, 200, 250, and 300 may be implanted into a patient using various approaches, however, it is preferred that the devices 10, 50, 80, 100, 150, 200, 250, and 300 are implanted either posterior-laterally or laterally to avoid complications that may be associated with anterior surgery. A unilateral, minimally invasive approach and technique may be used to insert the devices 10, 50, 80, 100, 150, 200, 250, and 300 into a patient. The fusion cage devices 10, 50, 80, 100, 150, 200, 250, and 300 may also be packed with autologous bone to assist in fusion. Some of the devices 10, 50, 80, 100, 150, 200, 250, and 300 may include channels which allow for internal packing of autologous bone pieces. In addition or alternatively, autologous bone pieces may be inserted around the devices 10, 50, 80, 100, 150, 200, 250, and 300 after implantation to assist with fusion of the vertebrae.

The devices 10, 50, 80, 100, 150, 200, 250, and 300, discussed above, may more accurately engage the anatomy of the intervertebral disc space, thus decreasing the incidence of pseudoarthrosis and cage migration. The devices 10, 50, 80, 100, 150, 200, 250, and 300 also allow for oblique expansion which may allow for unilateral application of the devices 10, 50, 80, 100, 150, 200, 250, and 300 to the intervertebral body space using a minimally invasive approach. In addition, the expanding members, discussed above with reference to devices 10, 50, 80, 100, 150, 200, 250, and 300, allow for insertion and removal, if necessary, of the devices 10, 50, 80, 100, 150, 200, 250, and 300.

The invention has been described with reference to the preferred embodiments. It will be understood that the architectural and operational embodiments described herein are exemplary of a plurality of possible arrangements to provide the same general features, characteristics, and general system operation. Modifications and alterations will occur to others upon a reading and understanding of the preceding detailed description. It is intended that the invention be construed as including all such modifications and alterations. 

Having thus described the preferred embodiments, the invention is now claimed to be:
 1. An oblique expanding fusion cage device, comprising: a body with a superior portion and an inferior portion, wherein the superior portion and the inferior portion each have a proximal end and a distal end; a pathway extending from the proximal end to the distal end between the superior portion and inferior portion; an opening separating the superior portion and the inferior portion and overlapping the pathway; and an expanding member removably inserted into the pathway and moveable toward the distal end of the body, wherein the expanding member engages the superior portion and the inferior portion as the expanding member moves distally within the pathway, wherein an exterior of the body is narrower at the distal end than at the proximal end along a dimension of an exterior surface of the superior and inferior portions that extends across the pathway in an undeployed position.
 2. The oblique expanding fusion cage device of claim 1, wherein the body has a generally trapezoidal shape.
 3. The oblique expanding fusion cage device of claim 1, wherein the pathway extends through the opening.
 4. The oblique expanding fusion cage device of claim 1, wherein the pathway is threaded and the expanding member includes threading that engages with the pathway threading.
 5. The oblique expanding fusion cage device of claim 1, wherein the pathway tapers from the proximal end to the distal end.
 6. The oblique expanding fusion cage device of claim 1, wherein the opening includes a locking mechanism for locking the expanding member when fully inserted in the device.
 7. An oblique expanding fusion cage device, comprising: a first arm and a second arm each having a proximal end and a distal end; an expanding member positioned between the first arm and the second arm, the expanding member comprising: a body portion at a proximal end of the device; and a wedge portion at a distal end of the device; wherein the proximal end of each of the first and second arms are pivotally coupled to the body portion; and a winding mechanism located at the proximal end of the first and second arms, wherein the winding mechanism is coupled to the body portion of the expanding member.
 8. The oblique expanding fusion cage device of claim 7, wherein the first arm and the second arm are hingedly coupled to the body portion at the proximal end of the first and second arms.
 9. The oblique expanding fusion cage device of claim 7, wherein the winding mechanism includes a cable extending between the winding mechanism and the wedge, and wherein the cable is adapted for pulling the wedge towards the proximal end of the first and second arms.
 10. The oblique expanding fusion cage device of claim 9, wherein the cable is positioned between the first arm and the second arm and extends parallel to the first arm and the second arm in an undeployed position.
 11. The oblique expanding fusion cage device of claim 7, wherein the first arm is coupled to the body portion of the expanding member with a first pivot pin and the second arm is coupled to the body portion of the expanding member with a second pivot pin.
 12. A surgical method for maintaining an interbody space in a spine of a patient, comprising: obtaining a medical device comprising: a body with a superior portion and an inferior portion, wherein the superior portion and the inferior portion have a proximal end and a distal end, the inferior portion comprises at least one protrusion extending toward the superior portion, and the superior portion comprises at least one opening adapted to receive the at least one protrusion, wherein the superior portion has an interior portion with a semicircular cross-sectional shape and the inferior portion has an interior portion with a semicircular cross-sectional shape, and wherein at least a portion of the interior portion of the superior portion overlaps with at least a portion of the interior portion of the inferior portion, the superior portion having a planar contact surface and the inferior portion having a planar contact surface for engaging vertebrae; a pathway extending from the proximal end of the body to the distal end of the body between the superior portion and inferior portion; an opening separating the superior portion and the inferior portion in the proximal end of the body and overlapping the pathway, and enabling access to the pathway; and an expanding member removably inserted into the opening and moveable toward the distal end of the body, wherein the expanding member engages the superior portion and the inferior portion as the expanding member moves distally within the pathway; inserting the medical device into a patient through an opening in the skin; positioning the medical device in the interbody space; inserting the expanding member into the body; and deploying the distal end of the medical device into a deployed position to engage two vertebrae adjacent the interbody space, wherein the body is narrower at the distal end than at the proximal end along a dimension that extends across the pathway in an undeployed position.
 13. The surgical method for maintaining an interbody space in a spine of a patient of claim 12, wherein inserting the medical device into the patient includes using an approach selected from posterior-laterally and laterally.
 14. The surgical method for maintaining an interbody space in a spine of a patient of claim 12, wherein inserting the medical device into the patient includes using a unilateral, minimally invasive approach. 